U.S. patent number 8,850,871 [Application Number 12/894,619] was granted by the patent office on 2014-10-07 for pipeline leak location using ultrasonic flowmeters.
This patent grant is currently assigned to Siemens Aktiengesellschaft. The grantee listed for this patent is Dennis J. Diorio, James M. Doorhy, Robert Schaefer. Invention is credited to Dennis J. Diorio, James M. Doorhy, Robert Schaefer.
United States Patent |
8,850,871 |
Schaefer , et al. |
October 7, 2014 |
Pipeline leak location using ultrasonic flowmeters
Abstract
Fluid leaks are identified and located by successively
monitoring changes in fluid flow and sound velocities of fluid at a
plurality of locations in the pipe with flow meters, such as with
ultrasonic flow meters. Preferably the successive monitoring
sampling rates are sufficiently high to measure instantaneous
velocity changes. A controller coupled to the meters associates
changes in monitored fluid flow and sound velocities in two
locations along the pipe with a leak event occurring between those
locations. The controller identifies the association event at each
location and correlates pipe leak location based at least in part
on difference in time between the respective location events. The
system and method may be used in liquid and gas pipeline
transmission systems.
Inventors: |
Schaefer; Robert (Northport,
NY), Diorio; Dennis J. (Kings Park, NY), Doorhy; James
M. (Manorville, NY) |
Applicant: |
Name |
City |
State |
Country |
Type |
Schaefer; Robert
Diorio; Dennis J.
Doorhy; James M. |
Northport
Kings Park
Manorville |
NY
NY
NY |
US
US
US |
|
|
Assignee: |
Siemens Aktiengesellschaft
(Munich, DE)
|
Family
ID: |
44681419 |
Appl.
No.: |
12/894,619 |
Filed: |
September 30, 2010 |
Prior Publication Data
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|
|
Document
Identifier |
Publication Date |
|
US 20120079872 A1 |
Apr 5, 2012 |
|
Current U.S.
Class: |
73/40.5A |
Current CPC
Class: |
G01M
3/2807 (20130101); G01M 3/243 (20130101) |
Current International
Class: |
G01M
3/24 (20060101) |
Field of
Search: |
;73/40.5A |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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2895508 |
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Jun 2007 |
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FR |
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2289760 |
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Nov 1995 |
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GB |
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WO 2008016697 |
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Feb 2008 |
|
WO |
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WO 2009132865 |
|
Nov 2009 |
|
WO |
|
Other References
PCT International Search Report mailed Nov. 23, 2011 corresponding
to PCT International Application No. PCT/US2011/050126 filed Sep.
1, 2011 (12 pages). cited by applicant.
|
Primary Examiner: Williams; Hezron E
Assistant Examiner: Redmann; Gregory J
Claims
What is claimed is:
1. A pipe leak detection system, comprising: a plurality of meter
pairs, each respective pair having a fluid flow meter and a sound
velocity meter at a plurality of locations along a common pipe,
each pair successively monitoring respective changes in fluid flow
and sound velocities of fluid in the pipe, and each pair comprising
a meter controller; and a master controller, coupled to the meter
controllers of the meter pairs, for associating changes in
monitored fluid flow and sound velocities by two of the meter pairs
at two locations along the common pipe with a leak event in the
pipe occurring between those locations, wherein each meter
controller gathers samples of both sound velocity and fluid flow
velocity, records time of each sample and periodically transmits
batches of samples to the master controller, wherein the master
controller receives time-stamped fluid flow and sound velocities
data from each meter controller of the meter pairs and associates
changes in the time-stamped fluid flow and sound velocities data
with a leak event.
2. The system of claim 1, wherein the respective meter pairs are
non-intrusively coupled to the pipe exterior.
3. The system of claim 2, wherein the respective meter pairs are
ultrasonic flow control meters capable of monitoring both flow and
sound velocities.
4. The system of claim 1, wherein a plurality of respective
velocities samples and their sample times are collected by the flow
meters in each meter pair and periodically sent to the master
controller.
5. The system of claim 1, wherein the time of each meter pair
location leak event is communicated to the master controller, and
time clocks at each meter pair location are synchronized.
6. The system of claim 1, further comprising greater than two meter
pairs, the controller correlating pipe leak location events with
two meter pairs having shortest relative sample times.
7. A pipe leak detection and location system, comprising: a
plurality of meter pairs, each respective pair having a fluid flow
meter and a sound velocity meter at a plurality of locations along
the a common pipe, each pair successively monitoring respective
changes in fluid flow and sound velocities of fluid in the pipe,
and each meter pair comprising a meter controller, wherein each
meter controller gathers samples of both sound velocity and fluid
flow velocity and records time of each sample; and a master
controller, coupled to the meter controller of the meter pairs,
for: receiving time-stamped fluid flow and sound velocities data
from each meter controller of the meter pairs; associating changes
in the fluid flow and sound velocities data gathered by meter
controllers of two adjacent meter pairs at two locations along the
common pipe with a leak event in the pipe occurring between the two
locations; and determining a location of the leak event by
correlating a difference in sample time between the two adjacent
meter pairs, based upon a shortest time difference upstream and
downstream of the leak event, with the changes in the fluid flow
and sound velocities data of the two adjacent meter pairs.
8. The system of claim 7, wherein the respective meter pairs are
non-intrusively coupled to the pipe exterior.
9. The system of claim 8, wherein the respective meter pairs are
ultrasonic flow control meters capable of monitoring both flow and
sound velocities.
10. The system of claim 7, wherein a plurality of respective
velocities samples and their sample times are collected by the flow
meters and periodically sent to the controller.
11. The system of claim 7, wherein the time of each identified
location leak event is communicated to the controller, and time
clocks at each meter pair location are synchronized.
12. The system of claim 7, wherein the successive monitoring of
changes of sound and fluid flow velocities at plural locations
comprises monitoring of instantaneous changes in velocities at a
sampling update rate of 1 to 50 milliseconds with the respective
flow meters.
13. The system of claim 7, further comprising greater than two
meter pairs, the controller correlating pipe leak location with two
adjacent meter pairs having the shortest relative sample times.
Description
BACKGROUND OF THE DISCLOSURE
1. Field of the Invention
The invention relates to pipe leak detection and location systems
and methods. Exemplary applications are suitable for leak detection
and location in oil, natural gas and other pipelines that transport
gaseous or liquid fluids over long geographic distances.
2. Description of the Prior Art
In order to implement environmental, health and safety policies,
pipeline owners and operators monitor pipelines for leaks. When a
leak is identified, the leaking pipe segment must be located,
isolated and repaired as quickly as possible, so as to minimize
loss of material and potential environmental infiltration. Often
pipelines are routed through remote geographic areas or buried
underground or beneath waterways, making external visual inspection
difficult or impossible. In the past various remote leak detection
and location methods have been employed to satisfy pipeline
monitoring needs.
As shown in FIGS. 1A-1C, when pipes 10 experience a leak 12, the
leak event causes upstream and downstream pressure wave
disturbances 14 that propagate at the fluid's sound velocity C,
also notated as V.sub.s in technical literature. The pressure wave
disburbance 14 is caused by sudden loss of pressure at the leak
site, and travels upstream and downstream. As a pressure wave
propagates through a given fluid volume, it alters the fluid's
local density, thus modifying as a function of time the local sound
velocity as well as the fluid flow velocity V.sub.f.
The assignee of the present application and its predecessor
companies have developed, patented and sold leak monitoring and
detection systems utilizing ultrasonic flow meters oriented at
selected monitoring locations ("Loc") along a pipeline. As shown
and described in U.S. Pat. Nos. 5,548,530 and 6,442,999, the entire
contents of each being incorporated herein by reference, ultrasonic
meters at each location periodically monitor, measure and record
sound velocity C with a time stamp that is forwarded to a central
station controller. The time clock at each location is periodically
synchronized in cooperation with the controller, so that C
measurements at each location can be compared and analyzed by the
controller with a common time reference line. As a leak pressure
wave disturbance anomaly propagates through the pipeline, upstream
and downstream monitoring locations will experience localized
variations in C caused by the disturbance at different times
generally correlating to distance L from the disturbance. The
controller identifies monitoring locations bracketing each side of
the leak and then extrapolates the leak location based at least in
part on difference in time between when each of the monitoring
locations identified the leak event causation of sound velocity C
change.
As noted in U.S. Pat. Nos. 5,548,530 and 6,442,999, ultrasonic flow
meters are non-intrusive and do not have to be installed inside a
pipe, as must be done with intrusive pressure transducers or
mechanical flow rate transducers, such as in U.S. Pat. No.
5,272,646. Non-intrusive metering does not require pipe wall
penetration, preserving pipe integrity, and lowering initial or
retrofit installation costs.
Generally the ultrasonic flow meter leak detection and location
methods and systems shown in U.S. Pat. Nos. 5,548,530 and 6,442,999
enable rapid identification and location of leaks within several
hundred feet (100 meters) of location error between monitoring
locations spanning distances of up to approximately 50 miles (75
kilometers). However in some applications leak identification and
location solely based on monitoring change in sound velocity C is
difficult because of the leak propagation disturbance wave
attenuation, as shown in FIGS. 1A-1C.
In FIG. 1A, pipe 10 discharges into an atmospheric pressure tank
16. The localized line pressure at LocB is too low for strong
propagation of the leak wave 14, so that there may be an
insignificantly measureable variation in sound velocity C.sub.B.
Thus, while LocA may measure a sound velocity variation C.sub.A,
the location of the leak 12 between LocA and LocB is not as
reliably extrapolated within a low desired error probability as can
be done between monitoring locations having higher localized
pressures.
In FIG. 1B the relative distance between leak 12 and monitoring
location LocD is very large. Leak disturbance wave 14 propagation
attenuation makes it more difficult to identify a leak event at
LocD, especially for fluids having low density, e.g., low pressure
gas transmission. A practical solution may be to reduce the
distance between monitoring locations at the cost of additional
meter installations, maintenance and monitoring. It is desirable to
maximize rather than reduce distance between monitoring
locations.
FIG. 1C is another exemplary challenge to accurate sound velocity
monitoring in lower density or pressure fluids. In FIG. 1C pipeline
10 is serially transporting a relatively high density FLUID 1 ahead
of an upstream lower density FLUID 2, with a known buffer fluid
separating the two fluid streams. Leak 12 erupts within the FLUID 1
stream and generates leak propagation disturbance 14, monitored and
identified at LocF as a change in C.sub.F. However, the upstream
propagation wave 14 detected as a change in C.sub.E at LocE is
traveling through less dense FLUID 2. Depending on the degree of
upstream leak disturbance attenuation, it may be more difficult to
identify that leak disturbance event at LocE, and differences in
transmission propagation speed in FLUID 2 compared to FLUID 1 will
make it more difficult to extrapolate to desired accuracy the
location of leak 12 at the proper distances L.sub.E and
L.sub.F.
Leak disturbances also alter localized flow velocity V.sub.f,
generally increasing upstream velocity and lowering downstream
velocity, due to lower pumping resistance at the leak site. In U.S.
Pat. No. 5,272,646 it is stated that both pressure and flow rate
through an invasive differential pressure meter can be monitored at
plural locations to locate a pipeline leak. It also has been
observed by the present inventors that localized flow velocity
V.sub.f changes caused by leak pressure wave disturbances are
identifiable when localized pressure at a measurement location is
low or at greater distances from the leak location, compared to
what can be identified by change in sound velocity C alone. They
have noted that monitoring of both change in sound velocity and
fluid flow velocity increased leak identification and location
confidence. The leak disturbance may be identified by change in
sound velocity or change in flow velocity. Contemporaneous
identification and corroboration by both measurement modalities
greatly increases identification and location confidence. However,
known flow velocity meters require intrusion into the pipe.
Thus, a need exists in the art for a pipe leak detection and
location system and method that utilizes non-intrusive
instrumentation located outside of the pipe.
Another need exists in the art for a pipe leak detection system and
method that monitors changes in fluid flow and sonic velocities, at
plural locations in the pipe, and that associates changes in either
with a leak event between two of the monitored locations.
Yet another need exists in the art for a pipe leak detection and
location system and method that monitors changes in fluid flow and
sonic velocities, at plural locations in the pipe that associates
changes in either with a leak event between two of the monitored
locations and further enables precise leak location
identification.
SUMMARY OF THE INVENTION
Accordingly, an object of the present invention is to create a pipe
leak detection and location system and method that utilizes
non-intrusive instrumentation located outside of the pipe, with
higher leak detection reliability than previously known
systems.
Another object of the present invention is to create a pipe leak
detection system and method that monitors changes in fluid flow and
sound velocities, at plural locations in the pipe, and that
associates changes in either with a leak event between two of the
monitored locations.
Yet another object of the present invention is to create a pipe
leak detection and location system and method that monitors changes
in fluid flow and sonic velocities, at plural locations in the
pipe, that associates changes in either with a leak event between
two of the monitored locations and also enables precise leak
location identification.
These and other objects are achieved in accordance with the present
invention by the leak detection and location systems and methods of
the present invention that monitor changes in fluid flow and sonic
velocities of fluid at a plurality of locations along a pipe.
Changes in monitored fluid flow and sonic velocities in any two
locations are associated with a leak event occurring between them.
The event time at each of the two locations is noted. The leak
location is determined by using difference in time between the
events at each of the respective locations to correlate where the
leak would have to be located in order for the leak disturbance
propagation wave to reach each of the monitoring locations at their
respective recorded event times.
One aspect of the present invention is directed to a method for
fluid leak detection in a pipe featuring successively monitoring
changes in fluid flow and sonic velocities of fluid at a plurality
of locations along the pipe with flow meters. Changes in monitored
fluid flow and sonic velocities in two locations along the pipe are
associated with a leak event occurring between those locations by a
controller coupled to the flow meters. The controller identifies
time of the respective association of event sampled at the two
locations. Furthermore, the leak position on the pipe can be
correlated at least in part on difference in time between the
respective location events, so that it can be determined where the
leak event must have originated in order for the leak disturbance
propagation wave to reach each of the monitoring locations at their
respective recorded event times.
Another aspect of the present invention is directed to a pipe leak
detection and location system, featuring a plurality of pairs of
fluid flow and a sound velocity meters at a plurality of locations
along the pipe. Each meter pair successively monitors respective
changes in fluid flow and sonic velocities of fluid in the pipe. A
controller is coupled to the meter pairs. The controller associates
changes in fluid flow and sonic velocities monitored by the meter
pairs at two locations along the pipe with a leak event occurring
between those locations. The controller identifies the respective
association of event sampled at the two locations. The controller
then correlates pipe leak location based at least in part on
difference in time between the respective location events, so that
it can be determined where the leak event must have originated in
order for the leak disturbance propagation wave to reach each of
the monitoring locations at their respective recorded event
times.
The meter pairs at each monitoring location are preferably
non-intrusively coupled to the pipe exterior. An ultrasonic flow
meter may be used to perform both sound velocity and fluid flow
velocity monitoring. The flow meters may collect monitoring samples
and periodically send batches of samples to the controller for
monitoring analysis.
The objects and features of the present invention may be applied
jointly or severally in any combination or sub-combination by those
skilled in the art.
BRIEF DESCRIPTION OF THE DRAWINGS
The teachings of the present invention can be readily understood by
considering the following detailed description in conjunction with
the accompanying drawings, in which:
FIG. 1A is a schematic view of an exemplary pipeline discharging
into an atmospheric pressure tank, with a leak monitoring location
proximal the tank;
FIG. 1B is a schematic view of an exemplary pipeline with a
relatively long distance between leak monitoring locations;
FIG. 1C is a schematic view of an exemplary pipeline transporting
different fluids in serial batches;
FIG. 2 is a schematic elevational view of an exemplary pipeline
having the pipe leak detection and location system of the present
invention; and
FIG. 3 is a schematic elevational view of a fluid flow monitoring
station of the present invention.
To facilitate understanding, identical reference numerals have been
used, where possible, to designate identical elements that are
common to the figures.
DETAILED DESCRIPTION
After considering the following description, those skilled in the
art will clearly realize that the teachings of the present
invention can be readily utilized in pipe leak detection and
location systems. An exemplary embodiment of the present invention
is shown in FIGS. 2 and 3.
General Description of System Architecture
FIG. 2 shows pipe 10 having an array of flow meters 20 arrayed
along its length as far apart as up to 100 miles (148 kilometers).
Referring to FIG. 3, each flow meter 20 is a non-invasive
ultrasonic flow meter of known construction and operation coupled
to the pipe 10 exterior. An exemplary ultrasonic flow meter is a
Model 7ME3600 sold in the United States of America by Siemens
Industry Solutions, Inc. The flow meter 20 has an upstream
transducer 22 and a downstream transducer 24 that are physically
separated a known distance and coupled to a meter controller 25
that includes software stored in memory 26 and a clock 27, which is
preferably a real time clock. The meter controller 25, implementing
the software stored in memory 26, causes the upstream transducer 22
to send an ultrasonic signal 28 through fluid in the pipe 10 at a
sampling rate established with the clock 27. The reflected signal
from upstream transducer 22 is detected by the downstream
transducer 24. The direction is then reversed such that the
downstream transducer sends an ultrasonic signal to the upstream
transducer. As is known by those skilled in the art, the time
difference between each direction of transmission and the average
time delay from transmission to receipt of the ultrasonic signal
can be correlated to both sound velocity C and flow velocity
V.sub.f of the fluid in the meter.
The meter controller 25 gathers samples of both sound velocity C
and fluid flow velocity V.sub.f and records time t of each sample.
Preferably samples are taken at a 1 to 50 millisecond update rate
for high resolution. The high sampling rate effectively enables the
meter 20 to determine the instantaneous change in fluid flow
velocity (dV.sub.f/dt) and sound velocity (dC/dt) in the fluid.
Real time samples may be collected in the meter controller 25 in
batches and periodically transmitted to master controller 30 at a
slower transmission rate; for example of the order of one batch per
minute. If desired, the sample batches can be compressed prior to
transmission to the master controller 30 using known data
compression techniques. The master controller subsequently
decompresses the received sample batches for further analysis and
processing. Data processing and analysis tasks can be divided
between the meter controller 25 and master controller 30 at the
discretion of one skilled in the art. Concentration of processing
tasks in the master controller 30 may reduce manufacture and
maintenance costs.
Master Controller 30 is of known construction. An exemplary master
controller is a Model 10LD sold in the United States of America by
Siemens Industry Solutions, Inc. Master controller 30 is
communicatively coupled to each meter controller 25 in the
respective meters 20 arrayed along the pipeline at designated
locations Loc(1), Loc(2) . . . Loc(N) in FIG. 2. Any known
communications coupling pathway may be utilized between the
respective controllers 25, 30, including by way of example
bi-directional data busses 40, hard wired lines 44 (including
carrier signals over power lines, fiberoptic, coaxial or metallic
communications cable, etc.) or wireless communication via antennae
42.
The master controller 30 includes a synchronization clock 32, which
is preferably a real time clock, and software stored in memory 34.
The master controller 30, implementing the software stored in
memory 34, receives time-stamped sound and fluid flow velocities
data from each of the meters 20 at locations Loc(1)-Loc(N). The
master controller 30 periodically sends clock synchronization
signals from the synchronization clock 32 to the respective meter
clocks 27 at each meter 20 location Loc, so that time samples from
each meter 20 have a common frame of reference. If desired, meter
clocks 27 and/or master controller synchronization clock 32 may be
synchronized by global positioning system (GPS) synchronization
clock 32.
General Description of Leak Location
Referencing FIG. 2, as previously noted herein, a leak event caused
at leak 12 within the pipe 10 causes upstream and downstream
pressure wave disturbances 14 that propagate at the fluid's sound
velocity C. As a pressure wave propagates through a given fluid
volume, it alters the fluid's local density, thus modifying over
time the local sound velocity C, as well as the fluid flow velocity
V.sub.f. The master controller 30 associates changes in sound and
fluid flow velocities samples captured by the meters 20 with a leak
12 event, and notes the time of each event at the respective meters
20. Based on the leak pressure wave propagation characteristics in
the pipe 10, the leak event may be detected by instantaneous change
in either sound or fluid flow velocities or both. The master
controller 30 correlates the difference in event time at the two
meter locations Loc.sub.(1) and Loc.sub.(2) closest to the leak
(i.e., the shortest time difference upstream and downstream of leak
12) with travel distances L.sub.(1) and L.sub.(2), such as by the
exemplary methods disclosed in U.S. Pat. Nos. 5,453,944 and
6,442,999.
The master controller 30 preferably utilizes sound velocity C and
flow velocity V.sub.f samples from each respective meter 20
location Loc to identify and track series of different fluid feeds
through the pipeline 10. Using the example of FIG. 1C, the
controller 30 associates passage of FLUID1 through the pipeline
based on correlation of sound velocity C characteristics with
different types of fluids. When LocE and upstream meter locations
detected a drop in C with the passage of FLUID2, the controller 30
modifies its analysis of pulsation wave 14 propagation
characteristics to compensate for the different physical
characteristics of FLUID2.
As one skilled in the art can appreciate, specific applications of
the present invention may dictate need for enhanced analysis of
respective change of velocities samples with known statistical data
processing techniques, in order to reduce likelihood of false leak
detections caused by spurious or transient velocity fluctuations.
For example, the master controller 30 may be programmed to require
that a flow or sound velocity function exist for a minimum number
of consecutive samples, or that windows of samples be averaged
repetitively before the fluctuation is associated with a leak
event. Similarly, the controller 30 may be programmed to ignore a
known pulsation pattern in the pipeline caused by another device
(e.g., valve closing or pump operation).
Although various embodiments which incorporate the teachings of the
present invention have been shown and described in detail herein,
those skilled in the art can readily devise many other varied
embodiments that still incorporate these teachings.
* * * * *